This project is a study of infants at high risk for obesity who are examined before the onset of the disorder (obesity), to try to determine what factors may lead to the development of the disorder. Such studies are of particular importance in the case of obesity, as most of what we know is based on the study of persons who are already obese and may be a consequence, not a cause, of obesity. the specific aims of the study are: (1) to test the hypothesis that total energy expenditure and resting metabolic rate of the three month old infants of obese mothers are lower than those of lean mothers. To test the corollary hypothesis that these lower rates of energy expenditure are predictive of adiposity at one, two and four years of age. (2) To test the hypothesis that a vigorous sucking style in infancy is associated with increased adiposity at one, two and four years of age. (3) To test the hypothesis that caloric consumption in infancy is related to the development of adiposity at one, two and four years of age. (4) To examine the interaction among the above variables in relation to the development of adiposity.